Originally posted by tamilselvan
Take your design.
CITY table
id varchar2(2)
name varchar2(30)

STATE table
id varchar2(2)
name varchar2(2)

How many timed do you encounter "columns are ambiguously defined error message"?
Never. At least not if you have some commonly accepted SQL coding standards in effect. No matter how unambigously your columns are named in your tables, you should still put table name (or alias) in front of your columns in SQL every time you use more than one table in your SQL.